1. Field of the Invention
The present application relates to a power transmission apparatus and a method for controlling the power transmission apparatus.
2. Discussion of the Background
If a vehicle is suddenly decelerated due to, for example, sudden braking (panic braking), the rotational speed of a drive axle is sharply reduced. In addition, a force of inertia that arises from the drive axle (i.e., from the road surface) increases sharply. If the transmission mounted in the vehicle is a continuously variable transmission, the force of inertia acts on the continuously variable transmission as an excess load.
Accordingly, Japanese Examined Patent Application Publication No. 6-76824 describes a technology that intentionally allows a belt to slip by decreasing an adjustment line pressure supplied to a hydraulic actuator of the continuously variable transmission to lower than a reference value when a sudden deceleration is detected.
Alternatively, a technology that allows a clutch to function as a torque limiter has been widely used. In such a technology, a hydraulic wet clutch is disposed in series to the continuously variable transmission, between the drive source and a drive axle. Even when an unforeseen load is imposed on the continuously variable transmission, slippage of the belt can be prevented by allowing the clutch to slip.